Biomechanical comparison of plate-screw and screw fixation in medial tibial plateau fractures (Schatzker 4). A model study.

INTRODUCTION: The objective of this biomechanical study was to compare the respective efficiency of plate-screw fixation and screw fixation in an experimental model of a Schatzker type 4 fracture. HYPOTHESIS: screw fixation and plate fixation have a similar load to failure. MATERIALS AND METHODS: This study compares the stability of Schatzker type 4 medial tibial plateau fractures fixed with either 36.5mm cancellous bone screw with a 16 mm threaded segment or with six-holed buttress T-plate-screw system. A Schatzker type 4 fracture was modeled on an artificial bone model. In a first group of 10 fracture models, following the anatomical reduction, fractures were stabilized with screws with washers. In the second group, of 10 fracture models, fractures were stabilized with T-plate. After fixation ascending axial compression was applied on bone models (Instron machine). RESULTS: Load bearing capacity was 1397.6+/-194.4N in the Group 1 and 2153.2+/-204.4N in the Group 2. The difference between the two groups was statistically significant (p<0.001). DISCUSSION: According to this result, experimental load bearing of bone models indicate that plate-screw fixation system has a significantly higher stabilization capacity than fixation with three screws alone. Our hypothesis was not confirmed. In order to maintain anatomical repositioning, plate-screw system is a more stable fixation method than the screw in medial tibial plateau fractures Schatzker 4 LEVEL OF EVIDENCE: 1.

Innervation pattern of the abductor digiti minimi muscle of the hand.

This cadaver study investigated the innervation patterns of the abductor digiti minimi in Guyon's canal. There was only one branch to the abductor digiti minimi in 22 of the 30 specimens. Two branches were found in three hands, and three branches in two. Three other variations were documented.

Histological and magnetic resonance imaging alterations after irradiation of meniscus using Holmium:YAG laser.

OBJECTIVE: The authors performed an experimental and a prospective clinical study to evaluate the histological and magnetic resonance imaging (MRI) alterations after irradiation of meniscus using holmium:YAG (Ho:YAG) laser VersaPulse Select 60 watts and InfraTome Delivery Systems 30 degrees Handpiece (spot size at fiber tip 0.4 mm; Coherent Medical, Palo Alto, CA). BACKGROUND DATA: Recently, some authors reported a few cases with articular cartilage damage or paraarticular osteonecrosis following arthroscopic knee surgery in which the laser was used to assist in the treatment of meniscal pathology. METHODS: Meniscus specimens in saline immersion were exposed to Ho:YAG laser irradiation. The laser wavelength was 2.1 microm and pulse duration was 250 microsec. Power settings were 1-1.5 joules per pulse and 10-15 Hz. Total laser energy used in these procedures was 2, 3.5, and 6 K joules. Eight patients with meniscal problems underwent arthroscopic partial meniscectomy using Ho:YAG laser. Total laser energy used for these surgeries was 1.5-2.5 K joules. MRI was performed preoperatively and at 6 months postoperatively. RESULTS: At higher energy levels (more than 3 K joules), separation of the gap between the collagen fibers, and a three-dimensional dispersion in the striation were observed on electron microscopic evaluation of meniscus specimens. No patient had abnormal signals in MRI (a sign of articular cartilage damage or osteonecrosis) following arthroscopic laser surgery. CONCLUSION: When higher energy level is required, conventional instruments should be preferred in the treatment of meniscal lesions. Laser should be reserved for the posteriorly located and smaller meniscal lesions.

In vivo response to biodegradable controlled antibiotic release systems.

In this study, the major goal was to evaluate in vitro and in vivo findings by macroscopy, radiology, and histology to determine the effectiveness of therapy of experimental implant-related osteomyelitis with antibiotic carrier rods constructed of microbial polyesters. The polymers used were poly(3-hydroxybutyrate-co-4-hydroxyvalerate) [P(3-HB-co-4-HB)] and poly(3-hydroxybutyrate-co-3-hydroxy- valerate) [P(3-HB-co-3-HV)]. Both the Sulperazone and the Duocid-P(3-HB-co-4-HB) rods with a drug to polymer ratio of 1:1 (w/w) were effective in treating the bone infection that was experimentally initiated by inoculation of a hemolytic strain of Staphylococcus aureus (coagulase positive; phage type 52/52b) together with metal implants into the medullary area of rabbit tibia. Macroscopical data revealed that the effectiveness of therapy was apparent at week 6 for all categories tested. Radiological findings with Duocid- and Sulperazone-loaded P(3-HB-co-4-HB) rods improved significantly when judged by changes in periosteal elevation, widening of bone shaft, new bone formation, and soft-tissue deformation after 6 weeks of implantation. Histologically the signs of infection were found to subside by weeks 3 and 6. Inflammatory cells were replaced with bone-forming cells upon treatment with Sulperazone-P(3-HB-co-4-HB) and Duocid-P(3-HB-co-4-HB). Osteoblastic activity was prominent. Intramedullary inflammation, although still present, started to be replaced by fibrous or bony tissue. Histological findings presented the subsidence of infection. In summary, the antibiotic-loaded biopolymeric rods appeared to have potential as a new controlled-release system for the treatment of implant related osteomyelitis and chronic osteomyelitis.

Treatment of intertrochanteric fractures by external fixation.

This study evaluates the results of intertrochanteric fractures of the femur treated by external fixation. One hundred and four intertrochanteric fractures of the femur were stabilized by external fixation over an 8 year period. Complete fracture healing was detected in all patients within 11.2 weeks. Varus malunions and more than 2 cm limb shortening were evaluated in 8 patients. Eight patients had permanent knee stiffness. A pin tract infection occurred in 13 patients. This technique is simple and safe. It allows the patients to mobilize earlier. External fixation in intertrochanteric fractures of the femur can be performed especially in elderly patients with stable and unstable fractures that can be reduced to anatomical or nearly anatomical position by closed methods.